ECN publication
Determination of anthropogenic and biogenic contribution to ambient volatile organic carbons
Published by: Publication date:
ECN 1-10-1998
ECN report number: Document type:
ECN-C--98-081 ECN publication
Number of pages: Full text:
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The ultimate goal of this project was to determine the ratio of biogenicand anthropogenic contribution to volatile organic emissions, based on the "1"4C activity ("1"4C/"12C ratio) found in ambient air samples and to shed light on the importance of anthropogenic contribution to VOC emissions. The basic assumption behind the calculations was that the highest "1"4C content can be found in purely biogenic material, the expected "1"4C level was that of the presently measured background level in purely biogenic materials. In order to achieve the ultimate goal of the project, several practical challenges needed to be taken, including the development of two new sampling methods for the collection of large-volume ambient air samples respectively for hydrocarbon and for carbonyl analysis. Also, the participants needed to improve the present state of art concerning analytical and sampling techniques. The correctness of the experimental methods was proved with laboratory intercomparison exercises and QA/QC samples. Sample preparation for "1"4 C analysis has been established for the target compounds. Hence, the present state of the art has progressed considerably in the field of collecting, handling and preparing large volume air samples, and considerable achievements have been made in the field of "1"4 C measurements to enable acquisition of data from very small samples. The data acquired was thoroughly and critically evaluated. A sizeable fraction of hydrocarbons as well as total VOC was found to be of biogenic sources: the lowest contribution found was 20% for hydrocarbons, but the overall biogenic contribution for total VOC was found to be between 50 to 60% in hydrocarbons and carbonyls at sampling location in Juelich (Germany), Aveiro (Portugal), as well as in Ispra and Castelporziano (both in Italy). Some remaining recommendations include collection and measurement of more samples to enable statistical evaluation of the data. Based on the experience compiled and the technical improvements achieved within the framework of this project, follow-up experiments can be carried out with considerably less effort. 139 refs.

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